Re: [PATCH v2 05/15] xen/arm: segregate GIC low level functionality

[Julien Grall <julien.grall@linaro.org>]

On 04/09/2014 12:34 PM, Vijay Kilari wrote:
>> GICD_SGI_TARGERT_OTHERS will send an SGI to every CPUs even if the CPU is
>> not yet online (i.e. not registered by Xen). It's used during secondary boot
>> (cpu_up_send_sgi).
> 
> 
> cpumask_andnot(&all_others_mask,
> &cpu_possible_map,cpumask_of(smp_processor_id()));
> 
> In my understanding, with the above statement, I am using
> cpu_possible_map (all possible cpu's) which should
> contains all the cpu possible cpu masks. so this is fine.
> 
> The issue could be in gic_send_sgi() call which is always "and" with
> cpu_online_map
> 
> static void gic_send_sgi(const cpumask_t *cpumask, enum gic_sgi sgi)
> {
>     unsigned int mask = 0;
>     cpumask_t online_mask;
> 
>     ASSERT(sgi < 16); /* There are only 16 SGIs */
> 
>     cpumask_and(&online_mask, cpumask, &cpu_online_map);
>     mask = gic_cpu_mask(&online_mask);
> 
>     dsb(sy);
> 
>     GICD[GICD_SGIR] = GICD_SGI_TARGET_LIST
>         | (mask<<GICD_SGI_TARGET_SHIFT)
>         | sgi;
> }
> 
> I think gic_send_sgi should be passed with absolute mask value
> and get rid of and'ing with cpu_online_map

It won't work... gic_cpu_mask will translate the set of CPU ID into a
set of GIC CPU ID.

The mapping is initialized by gic_cpu_init. This function is only called
when the CPU is booting. So the mask is invalid for offline CPU...

>>> -static void do_sgi(struct cpu_user_regs *regs, int othercpu, enum gic_sgi
>>> sgi)
>>> +static void do_sgi(struct cpu_user_regs *regs, enum gic_sgi sgi)
>>
>>
>> Why did you drop the othercpu here?
>>
> othercpu is not used at all. and also othercpu is computed with
> IAR fields #defines which is not required in this generic code.

It should not be part of this patch. Please send a separate patch for
this change.

Regards,

-- 
Julien Grall